4.2.2. Shared Network Attached Storage (NFS)

Network Attached Storage – typically NFS – is a commonly
used file-based storage system that is very suitable for the
installation of Oracle VM storage repositories. Storage
repositories contain various categories of resources such as
templates, virtual disk images, DVD iso files and virtual
machine configuration files, which are all stored as files in
the directory structure on the remotely located, attached file
system.

With Oracle VM you discover NFS storage via the server IP or
host name and typically present storage to all the servers in a
server pool to allow them to share the same resources. This,
along with clustering, helps to enable high availability of your
environment: virtual machines can be easily migrated between
host servers for the purpose of load balancing or protecting
important virtual machines from going off-line due to hardware
failure.

NFS storage is exposed to Oracle VM Servers in the form of shares on the
NFS server which are mounted onto the Oracle VM Server's file system.
Since mounting an NFS share can be done on any server in the
network segment to which NFS is exposed, it is possible not only
to share NFS storage between servers of the same pool but also
across different server pools.

In terms of performance, NFS is slower for virtual disk I/O
compared to a logical volume or a raw disk. This is due mostly
to its file-based nature. For better disk performance you should
consider using block-based storage, which is supported in
Oracle VM in the form of iSCSI or Fibre Channel SANs.